octane and timing

[coolmite]

  Hi , I have a question about fuel.If I run 100 octane racing fuel instead of 92 octane with an octane booster would that require a timing change or advancement? I finally got my 440 six pack running decent, not great but the best its been since ive owned it.Yesterday I put in some 100 octane about 7 gallons on top of maybe 2 gallons of 92 octane.After a few miles car wasnt running as well, hesitating on acceleration and barely will idle.A friend told me the timing needs to be changed, Is that correct?

[Chryco Psycho]

if the engine will not ping with the timing set at 36* at 3000 RPM then adding any more octane will not help , high octane fuels are harder to burn
if it does ping with timing set at 36* & or you have the timing retarded to keep it from pinging higher octane will help & the timing does need to be advanced

[coolmite]

    Thanks for responding Chryco, I have a 1969 charger rt 440 sixpack, original 4 barrel. I dont have a timing light but advanced the timing a little bit and it idled really good ,  Seems to have fixed it for now anyway.The car is fast now, with the sixpack fine tuned it would be almost scary.

[deputycrawford]

Coolmite, get a timing light on that thing PRONTO. Its better to spend $70 on a brand new timing light or borrow someone elses than to spend another $1000 to fix burnt pistons and re-hone or bore a block.

[coolmite]

Deputycrawford thanks for the info.I don't know a whole lot about engines, just learning now.The last thing I can afford to do is move backwards in progress on this Mopar. Does the timing need to be right on 36* or it will cause damage? Seems to run pretty good, but Ill find a light to get it perfect.Thanks again.

[deputycrawford]

The average 440 seems to like 36 degrees but you will want to see what your specific engine likes. 36 degrees is the total mechanical timing. Thats with the vacum advance unplug from the distributor and plugged with some sort bolt in the hose or the carb nipple capped. Search the tech section and you will find the procedure for timing the engine. You might just pay the money and have a mechanic show you the first time. You don't want the engine to detonate and take peices of piston go with it. I just saw a race motor at my engine builders two days ago and he had too much timing in it. It let go near the end of the race. There is not much that can be saved. Money spent now will be money saved later.